This work studies the effects of the prefilter bandwidth on the symbol synchronizers of closed loop. The prefilter changes its bandwidth B, first B1=∞ (infinite), after B2=2.tx and next B3=1.tx, tx is the bit rate. The symbol synchronizer is based on a closed loop blocks. We consider four types, namely, the analog (ana), hybrid (hib), combinational (cmb) and sequential (seq). The objective is to study the prefilter bandwidth with the four symbol synchronizers and to evaluate their output jitter UIRMS (Unit Interval Root Mean Square) versus input SNR (Signal to Noise Ratio).